The invention relates to improvements in methods of an apparatus for treating elongated flexible laminates of the type having an elongated web of paper, artificial cork or the like and a film of an adhesive at least partially coating one side of the web. Laminates of such character can be utilized with advantage in so-called filter tipping machines for the making of filter cigarettes, cigarillos, cigars or the like (hereinafter referred to as filter cigarettes).
It is customary to make filter cigarettes by placing plain cigarettes of a unit length or multiple unit length end-to-end with rod sections (i.e., with filter plugs or filter muthpieces) for tobacco smoke, and by thereupon convoluting discrete adhesive-coated uniting bands around the abutting ends and the neighboring portions of the thus assembled pairs of rod-shaped constituents of filter cigarettes.
It is also customary to enhance the permeability of adhesive-coated uniting bands prior or subsequent to draping of such uniting bands around the pairs of coaxial rod-shaped components of filter cigarettes. This normally involves the making of perforations in the convoluted uniting bands or in the laminate which is to be subdivided into a series of discrete uniting bands. An advantage of such perforations is that the column of tobacco smoke flowing from the lighted end of a filter cigarette into the lungs of a smoker is mixed with relatively cool atmospheric air which is being drawn through the perforations. This is believed to be beneficial to the smoker. Reference may be had, for example, to U.S. Pat. No. 4,281,670 granted Aug. 4, 1981 to Uwe Heitmann et al. for "APPARATUS FOR INCREASING THE PERMEABILITY OF WRAPPING MATERIAL FOR ROD-SHAPED SMOKERS' PRODUCTS". This patent shows and describes perforating apparatus which are designed to make perforations in a running strip of uncoated tipping paper as well as apparatus for the making of holes in discrete uniting bands which are already convoluted around pairs of coaxial rod-shaped products, e.g., around the abutting ends of coaxial plain cigarettes and filter mouthpieces of unit length or multiple unit length.
In order to ensure reliable and predictable adherence of a convoluted uniting band to the adjacent portions of cigarette paper surrounding a plain cigarette as well as to the adjacent portions of the wrapper of a filter mouthpiece, one side of the running web of tipping paper or the like is coated with a suitable adhesive, e.g., shortly or immediately upstream of the perforating station or immediately following the perforating step and prior to subdivision of the perforated and adhesive-coated web into a series of discrete uniting bands. It is advisable to avoid the application of adhesive to those portions of a perforated web of tipping paper which are immediately adjacent the perforations and/or the transversely extending strip-shaped zones flanking the locations where the web is being subdivided into discrete uniting bands because this reduces the likelihood of clogging the perforations with activated adhesive and/or of contamination of the regions of overlap of marginal portions of convoluted uniting bands. A clogging of the perforations with an activated adhesive defeats the purpose of the perforations, and contamination of the overlapping marginal portions of convoluted adhesive-coated uniting bands detracts from the appearance of filter cigarettes.
Furthermore, the application of adhesive to one side of a running web of tipping paper in such a way that the regions immediately surrounding the perforations and the regions adjacent the severed zones of the running web are not coated with adhesive contributes significantly to the cost of the adhesive applying apparatus. Thus, the controls for the adhesive applicator are complex and expensive; in addition, such apparatus cannot always ensure the establishment of adhesive-free regions at the perforations and at the loci of subdivision of the web into discrete uniting bands.